Pupil-only photochromic contact lenses displaying desirable optics and comfort

ABSTRACT

A method for making a hydrogel, photochromic contact lens including supplying a first lens composition comprising a contact lens monomer and a photochromic material to a front contact lens mold and supplying a second lens composition to said contact lens mold wherein the viscosity of said first composition is at least about 1000 cp greater than the viscosity of said second contact lens composition, and the makeup of said second composition matches the of said first composition to reduce strain between said compositions of the resulting lens.

RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.13/082,447 filed Apr. 8, 2011, now, U.S. Pat. No. 8,697,770 issued Apr.15, 2014; which claims priority to provisional U.S. Patent ApplicationSer. No. 61/323,410, filed Apr. 13, 2010.

TECHNICAL FIELD

The present invention relates to contact lens eyewear and, moreparticularly, to contact lenses with photochromic dyes disposed in theregion of the lens covering the pupil region when worn, the photochromiccontact lenses having improved cosmetic appearance and improvedstructural qualities. The invention also relates to methods andmaterials used for making such photochromic contact lenses.

BACKGROUND INFORMATION

Early contact lenses have been known with photochromic liquid held in areservoir disposed between two materials forming a contact lens as partof a protective system against intense flashes such as a nucleardetonation.

More recently, efforts have been directed towards photochromic contactlenses that can be worn daily and that quickly transition betweencolored and uncolored states utilizing photochromic dyes capable ofabsorbing light in specific wavelength ranges. In some examples, a dyeis dispensed in a lens capable of exhibiting photochromism in thepolymeric material comprising the contact lens so as to preferably havea single layer capable of absorbing light. However the contact lensesthat exhibit photochromism throughout the entire lens area,“edge-to-edge”, are not desired due to cosmetic reasons.

Therefore, efforts have been made to create a contact lens that changescolor only in the central pupil region, “pupil-only” contact lens.

US2003/0142267 discloses contact lenses having a photochromic materialin the center or pupil region of the lens only. The lens is made bydispensing monomer mixes having different viscosities into the lensmold. The contact lenses are hard contact lenses which have no watercontent. The process disclosed in US2003/0142267 does not produce soft,hydrogel contact lenses which have desirable properties such as goodoptics and comfort.

There is a need for an improved pupil only photochromic contact lens,including a method of manufacturing such lenses, that exhibits reduceddeformation and optical distortion and increased comfort, wear ability,and cosmetic appearance.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is disclosed with reference to the accompanyingdrawings, wherein:

FIGS. 1A and 1B schematically represent methods of making pupil onlyphotochromic lenses according to the invention.

FIG. 2 is an exemplary lens made according to the methods of theinvention.

FIG. 3 shows an interferogram of a contact lens according to theinvention.

FIG. 4 is an exemplary lens according to the invention.

FIGS. 5-8 are photographs of the lenses of Examples 12, ComparativeExamples 1 and 2 and Example 13.

FIG. 9 is a schematic of the apparatus used to measure the deviation ofsagittal depth from the design sagittal depth in the examples.

DETAILED DESCRIPTION

As used herein hydrogels are water swellable polymers which have watercontents between about 20 and about 75% water.

As used herein reactive mixture or monomer mixture means

As used herein, expansion factor or swell is the change in dimension ofa hydrogel article after hydration. Expansion factor may be calculatedby dividing the diameter of hydrated lens by the lens formed in the moldprior to extraction and hydration and multiplying by 100.

As used herein sagittal depth is the height of a contact lens, measuredat its center (vertex) and from a chord drawn across the lens at itsbase diameter. Known tests may be used to measure sagittal depth,including ISO 18369-3, using an ultrasound instrument (section4.1.4.2.3).

Generally, one way to manufacture soft, hydrogel contact lenses is tocast mold contact lenses in plastic molds. Typically there are two moldportions which, when assembled, form a cavity. A reactive mixture whichcures within the cavity forms a contact lens. Typically a first moldportion is dosed with the reactive mixture, and the second mold portionis placed on the first mold portion, and then the reactive mixture iscured. The reaction of the reactive mixture is commonly radiationactivated. The reactive mixture in the cavity cures e.g. polymerizesand/or crosslinks to form the contact lens. The cured hydrogel contactlens is then removed from the molds and put in a solvent to remove theundesired chemical components. The lens normally swells in the process.The lens is then brought into contact with water to exchange the solventwith water, and give the hydrogel its final, stable shape and size.

Specifically referring to FIG. 1, two methods of manufacturing pupilonly photochromic contact lenses are schematically shown. In the firstmethod shown in FIG. 1a , a front curve 11 a is provided at step 10 a.The front curve 11 a is one part of the two part mold that is concave inshape so that the deposited material is held in the center of the moldby gravity. At step 12 a, a small and precise dose of photochromicdye-containing monomer mixture 13 a, or pupil monomer mixture, issupplied or dosed on a surface of the front curve mold 11 a preferablyin a substantially central location and in substantially circularconfiguration.

In one embodiment, the photochromic dye-containing monomer mixture isdosed in a central circular area within the optic zone of the contactlens. The central circular area may be the same size as the optic zone,which in a typical contact lens is about 9 mm or less in diameter. Inone embodiment, the central circular area has a diameter of betweenabout 4 and about 7 mm and in another between about 4 and about 6 mm indiameter.

Optionally, the photochromic dye-containing monomer mixture may be atleast partially polymerized through a controlled curing mechanism atstep 12 a. Then, a dose of clear monomer mixture, which does not containa photochromic dye, 15 a is dosed on the top of the photochromicdye-containing monomer mixture 13 a at step 14 a. The dose of clearmonomer mixture 15 a fills the concave front curve 11 a to the desiredamount and then, at step 16 a, the base curve 17 a is provided and themold halves 11 a, 17 a are put into their final curing position and themonomer mixtures are cured and/or polymerized completing the moldingprocess. Where the polymerization process includes aphoto-polymerization mechanism, the radiation, may be directed to eitherthe front curve mold half or the base curve mold half, or both. Themolded lens is then extracted to remove the un-desired chemicalcomponents and hydrated.

An alternative method is shown in FIG. 1b in which the first dose ofphotochromic monomer mixture 13 b is provided in the center of a frontcurve mold 11 b at step 12 b and then an annular ring of clear monomermixture 15 b is dosed at the edge of the front curve mold 11 b at step14 b. The resultant annular ring of clear monomeric material 15 b isdrawn to the center of the front curve by gravity. The base curve mold17 b is then supplied and the curing is initiated and completed at step16 b and the extraction and hydration step(s) (not shown) proceed toform the final hydrogel contact lens product.

In order to provide a hydrogel contact lens with acceptable separationof the two regions (print quality) and low distortion, generally interms of centralized photochromic dye 11 distribution, it has been foundthat, as described by US2003/0142267, increasing the viscosities of themonomer mixtures 13, 15 and, specifically, increasing the viscosity ofthe photochromic dye monomer mixture 13 as compared to the clear monomermixture 15, reduces molecular diffusion of the monomers 13, 15 therebymaintaining photochromic dye in the central region. Using a photochromicdye monomer mixture that has higher viscosity than the clear monomermixture helps to reduce the shear at the interface of the two monomersmixtures thereby reducing the physical mixing. An analysis of theStokes-Einstein equation, shown below, illustrates the parameters thataffect the diffusivity of a material:

$D = \frac{kT}{6{\pi\mu}\; r}$where, D is the molecular diffusivity, k the Boltzmann constant, T thetemperature, μ the viscosity and r the radius of the molecule. Operatingat lower temperatures and using monomers of higher viscosities tends toreduce the molecular diffusion rate. In one embodiment the viscosity ofthe photochromic dye monomer mixture is at least about 1000 cp higherthan the viscosity of the clear or peripheral monomer mixture and inanother embodiment at least about 1500 cp higher.

However, controlling the viscosity of the monomer mixtures as disclosedin US2003/0142267 was insufficient to provide hydrogel contact lenseshaving suitable optics and comfort. Hydrogel monomer mixtures when curedtogether produced contact lenses which displayed flattened optic zones,instead of lenses with a continuous radius. This may be measured bymeasuring the sagittal depth of the contact lens. Hydrogel lenses of thepresent invention have sagittal depths which are within about 100microns of the design sagittal depth for the lens. In one embodiment thedeviation from the design sagittal depth ranges from 0 (matched to thedesign sagittal depth) to −100 microns, which represents a slightflattening from the design sagittal depth.

It has been found that by balancing the expansion factor of the polymersformed from the photochromic dye monomer mixture and the clear monomermixture hydrogel contact lenses having desirable optics and comfort maybe produced. In one embodiment the expansion factors of the polymersformed from the respective monomer mixtures are within about 10% in someembodiments within about 8% and in other embodiments within about 5%.The expansion factor may be adjusted by manipulating a number offormulation variables including the diluent concentration, theconcentration and hydrophilicity or hydrophobicity of hydrophilic andhydrophobic components and concentration of initiator and crosslinker,and combinations thereof. Many photochromic dyes are highly hydrophobicand at the concentrations used in the present invention can have animpact on the expansion factor the hydrogels which contain them. In oneembodiment, where the photochromic dye is hydrophobic, it is added tothe formulation replacing a similar amount of another hydrophobiccomponent. Similarly, if the photochromic compound were hydrophilic itwill be added to the formulation replacing a similar amount of anotherhydrophilic component. In some embodiments, for example, where asilicone hydrogel contact lens is being produced, it may be desirable tomaintain the concentration of the silicone components and replace a partof one of hydrophilic components. In these embodiments, multipleadjustments may be needed to achieve the desired expansion factor.

In addition, other formulation variables may be modified to achieve thedesired expansion factor. In some embodiments varying the concentrationof the hydrophilic components, the diluent concentration and theinitiator concentration, and combinations thereof have been effective atproviding photochromic contact lenses having desirable optics andcomfort. In one embodiment a hydrophilic polymer, such as poly(vinylpyrrolidone) (PVP), methacrylic acid, polydimethylacrylamide orpoly(vinyl methacetamide) may be added to the photochromic dye monomermixture.

In some embodiments it is desirable to use the same or similarcomponents in both the photochromic dye and clear monomer mixtures. Forexample, it may be desirable to include the same hydrophilic componentsin both monomer mixtures. In this case, formulation variables inaddition to the concentration of hydrophilic components may be varied.The examples further illustrate how the formulation variables may bebalanced.

In one embodiment, where a single sided cure is used the expansionfactor is matched using monomers, diluent concentration and combinationsthereof. Where cure is effected from only one side (such as duringphotocuring), increasing the initiator concentration may also bedesirable.

The clear monomer mixtures 15 that may be employed in the inventioninclude soft contact lens materials made from HEMA based hydrogel orsilicone hydrogel materials, which include but are not limited tosilicone hydrogels, and fluorohydrogels. Examples of soft contact lensesformulations include but are not limited to the formulations ofetafilcon A, genfilcon A, lenefilcon A, polymacon, acquafilcon A,balafilcon A, galyfilcon A, senofilcon, narafilcon A, narafilcon B,comfilcon, filcon II 3, asmofilcon, Monomer A and lotrafilcon A, and thelike. Silicone hydrogels formulations, such as those disclosed in U.S.Pat. No. 5,998,498; U.S. patent application Ser. No. 09/532,943, acontinuation-in-part of U.S. patent application Ser. No. 09/532,943,filed on Aug. 30, 2000, and U.S. Pat. No. 6,087,415, U.S. Pat. No.6,087,415, U.S. Pat. No. 5,760,100, U.S. Pat. No. 5,776,999, U.S. Pat.No. 5,789,461, U.S. Pat. No. 5,849,811, U.S. Pat. No. 5,965,631, U.S.Pat. No. 7,553,880, WO2008/061992, US2010/048847, may also be used.These patents are hereby incorporated by reference for the hydrogelcompositions contained therein. In one embodiment contact lensformulations are selected from etafilcon A, balafilcon A, acquafilcon A,lotrafilcon A, galyfilcon A, senfilcon, comfilcon, narafilcon, Monomer Aand silicone hydrogels.

Additionally, suitable contact lenses may be formed from reactionmixtures comprising at least one silicone containing component. Asilicone-containing component is one that contains at least one[—Si—O—Si] group, in a monomer, macromer or prepolymer. Preferably, theSi and attached 0 are present in the silicone-containing component in anamount greater than 20 weight percent, and more preferably greater than30 weight percent of the total molecular weight of thesilicone-containing component. Useful silicone-containing componentspreferably comprise polymerizable functional groups such as acrylate,methacrylate, acrylamide, methacrylamide, N-vinyl lactam, N-vinylamide,and styryl functional groups. Examples of silicone components which maybe included in the silicone hydrogel formulations include, but are notlimited to silicone macromers, prepolymers and monomers. Examples ofsilicone macromers include, without limitation, polydimethylsiloxanemethacrylated with pendant hydrophilic groups.

Silicone and/or fluorine containing macromers may also be used. Suitablesilicone monomers include tris(trimethylsiloxy)silylpropyl methacrylate,hydroxyl functional silicone containing monomers, such as3-methacryloxy-2-hydroxypropyloxy)propylbis(trimethylsiloxy)methylsilane.

Additional suitable siloxane containing monomers include, amide analogsof TRIS. Vinylcarbanate or carbonate analogs, monomethacryloxypropylterminated polydimethylsiloxanes, polydimethylsiloxanes,3-methacryloxypropylbis(trimethylsiloxy)methylsilane,methacryloxypropylpentamethyl disiloxane and combinations thereof.

Exemplary photochromic materials that may be employed in someembodiments may include dyes mixed with contact lens materials, oralternately, polymerizeable monomers that are themselves photochromic.Other exemplary materials may include one or more of the following:polymerizable photochromic materials, such as polymerizablenaphthoxazines; polymerizable spirobenzopyrans; polymerizablespirobenzopyrans and spirobenzothiopyrans; polymerizable fulgides;polymerizable naphthacenediones; polymerizable spirooxazines;polymerizable polyalkoxylated naphthopyrans; and polymerizablephotochromic compounds.

Furthermore the photochromic materials may include in some embodiments,one or more of the following classes of materials: chromenes, e.g.,naphthopyrans, benzopyrans, indenonaphthopyrans and phenanthropyrans;spiropyrans, e.g., spiro(benzindoline)naphthopyrans,spiro(indoline)benzopyrans, spiro(indoline)naphthopyrans,spiro(indoline)quinopyrans and spiro(indoline)pyrans; oxazines, e.g.,spiro(indoline)naphthoxazines, spiro(indoline)pyridobenzoxazines,spiro(benzindoline)pyridobenzoxazines, spiro(benzindoline)naphthoxazinesand spiro(indoline)benzoxazines; mercury dithizonates, fulgides,fulgimides and mixtures of such photochromic compounds.

Other photochromic materials that may be useful in the invention includeorgano-metal dithiozonates, i.e., (arylazo)-thioformic arylhydrazidates,e.g., mercury dithizonates; and fulgides and fulgimides, e.g., the3-furyl and 3-thienyl fulgides and fulgimides. Non-limiting examples ofsuitable photochromic dyes include

The following examples and experiments illustrate certain aspects of thepresent invention, but they do not delineate or limit the invention.

EXAMPLES

The following abbreviations are used in the examples below:

Abbreviation Full Chemical Name SiGMA 2-propenoic acid,2-methyl-,2-hydroxy-3-[3-[1,3,3,3- tetramethyl-1-[(trimethylsilyl)oxy]disiloxanyl]propoxy]propyl ester HEMA2-hydroxyethyl methacrylate mPDMS 800-1000 MW (M_(n))monomethacryloxypropyl terminated mono-n-butyl terminatedpolydimethylsiloxane DMA N,N-dimethylacrylamide PVP poly(N-vinylpyrrolidone) (K value 90) Norbloc2-(2′-hydroxy-5-methacrylyloxyethylphenyl)-2H- benzotriazole CGI 819 1:1(wgt) blend of 1-hydroxycyclohexyl phenyl ketone andbis(2,6-dimethoxybenzoyl)-2,4-4-trimethylpentyl phosphine oxide BlueHEMA the reaction product of Reactive Blue 4 and HEMA IPA isopropylalcohol D30 3,7-dimethyl-3-octanol mPDMS-OHmono-(3-methacryloxy-2-hydroxypropyloxy)propyl terminated, mono-butylterminated polydimethylsiloxane (MW 1100) TEGDMA tetraethyleneglycoldimethacrylate TPME tripropylene glycol methyl etherMonomer Mixture A

Monomer mixture A was formed from the components listed in Table 1 anddiluent (D30) (77 wt % components:23 wt % D30).

TABLE 1 Components Wt % SiGMA 28 PVP (K90) 7 DMA 24 mPDMS 31 HEMA 6Norbloc 2 CGI 1850 0.48 TEGDMA 1.5 Blue HEMA 0.02Monomer Mixture B

Monomer mixture B was formed from the 55 wt % components listed in Table1 and 45 wt % diluent (a mixture of 55 wt % TPME and 45 wt % decanoicacid co-diluent).

TABLE 2 Monomer Components Monomers wt. % HO-mPDMS 55 TEGDMA 3 DMA 19.53HEMA 8.00 PVP K-90 12 CGI 819 0.25 Norbloc 2.2 Blue HEMA 0.02The Monomer mixture B formulations were degassed at about 600-700 mmHgfor approximately 30 minutes at ambient temperature prior to dosing.

Example 1

To demonstrate the feasibility for obtaining a pupil-only contact lensaccording to the method of FIG. 1 a, 20 mg ball-pen ink was mixed into 1g Monomer B monomer mixture listed in Table 2 to simulate thedye-containing pupil monomer and 3 mg of this monomer mixture was dosedinto the center of a front curve mold 10 c. The viscosity of the monomermixture was ˜3000 CP. Next, 80 mg of Monomer A monomer mixture was dosedon top of the pupil monomer mixture as shown in 14 c. The viscosity ofthe Monomer A monomer mixture was ˜300 CP. A base curve was thendeposited and the molds were closed and irradiated at 1.2 to 1.8 mW/cm²,under Philips TL K 40W/03 light bulbs in a nitrogen atmosphere for 25minutes at about 55±5° C.

The assembly was then cured resulting in the photo as shown in 16 c. Ascan be seen in FIG. 2, a very clear boundary of the two monomer mixtureswas observed.

Example 2

In this experiment, a photochromic dye of Formula I, made by PPGIndustries, was used.

5% photochromic dye was dissolved into a monomer mixture containing thecomponents listed in Table 2, and 45% TPME as diluent. For the clearmonomer mixture, Monomer B monomer mixture that contained 55% TPME asdiluent was used. The viscosity of this material was ˜400 CP. Themonomer mixtures were then cured under 2% oxygen environment for 20minutes, at 60° C. under 0.5 mW/cm2 intensity of Philips TL K 40W/03light bulbs. The base curve mold was then removed and the lens stayed inthe front curve mold. The lens and front curve mold assembly was droppedinto 90 C deionized water for 15 minutes to separate the lens from themold, and extract and hydrate the lens. The lens was then packaged inpackaging solution in glass vials and sterilized at 121° C.

The packing solution contains the following ingredients in deionizedH₂O: 0.18 weight % sodium borate [1330-43-4], Mallinckrodt; 0.91 weight% boric acid [10043-35-3], Mallinckrodt; 1.4 weight % sodium chloride,Sigma; 0.005 weight % methylether cellulose [232-674-9] from FisherScientific.

FIG. 3 shows the interferrograms of three exemplary lenses 30, 32, and34 produced in this Example 2. The interferrograms display smooth andcontinuous interference lines across the junctions between the lensportions formed from the two monomer mixtures. Accordingly, no obviousphysical distortions were observed in any of the produced lenses.

Example 3

In this Example, the clear monomer outer region was Monomer mixture A,Table 1 and the pupil monomer mixture containing photochromic dye wasbased on Monomer mixture A with 5% additional PVP (poly(N-vinylpyrolidone)) K90 added along with 6% photochromic dye. The additionalPVP K90 shifted the viscosity of Monomer mixture A from ˜300 CP to ˜1200CP which was sufficient to maintain a centralized optic zone containingphotochromic dye.

3 mg of the pupil monomer mixture was dosed into the center of a Zeonorfront curve lens mold. Next, 80 mg of monomer mixture A was dosed on topof the pupil monomer mixture. A polypropylene base curve was thendeposited on the front curve mold and the molds were closed. The filledmolds were irradiated using Philips TL 20W/03T fluorescent bulbs aboveand below the lens molds and the following conditions: about 1 minute atabout 1 mW/sec² at ambient temperature, about 7 minutes at 2 mW/sec² and80° C. and about 4 minutes at 5.5. mW/sec² and 80° C. All curing wasdone in N₂. The molds were opened and lenses were extracted into a 70:30(wt) solution of IPA and DI H₂O at ambient temperature for at least 60minutes. The IPA:DI water solution was exchanged twice, and soaked inIPA:DI water at ambient temperature for at least about 30 minutes foreach additional exchange to remove residual diluent and monomers, placedinto deionized H₂O for about 30 minutes, then equilibrated in boratebuffered saline for at least about 24 hours and autoclaved at 122° C.for 30 minutes.

A lens 40 according to this experiment is shown at FIG. 4. One outcomeof this experiment was that the addition of additional PVP K90 helped toshift the water content of the polymer in the pupil zone higher, therebycounterbalancing the reduction in water content caused by the additionof the hydrophobic photochromic dye. Accordingly, the degree ofhydration of the polymers formed from both the dye-containing monomermixture and the clear monomer mixture were in substantially conformity.Optical measurements indicate that the lenses created using this methodhave improved optic qualities.

Example 4

In this experiment, the clear monomer region was formed from Monomer Bmonomer mixture and the pupil region was formed from Monomer B materialwith photochromic dye. However in this experiment the viscosity wasadjusted by changing the concentration of the diluent component MonomerB monomer mixture to 45%. The 45% diluent in the clear region is made upof 40% tert-amyl alcohol and 60% decanoic acid while the 45% diluent inthe pupil monomer mixture was 100% decanoic acid. By modifying thediluents in this experiment the centering of the photochromic pupilregion was well contained within the central region of the optic zone.Additional this change allowed the viscosities to differ by ˜1800 cPbetween the inner (pupil) and outer (clear) regions while also providinga match in the swell of a hydrated lens in the two regions such thatgoods optics were obtained.

Example 5

A reaction mixture was formed from the components listed in Table 3 anddiluent (D30) (77 wt % components:23 wt % D30) (Reactive Mixture C).

Photochromic dye of Formula 1 (6 wt % based upon the weight of thereaction components of Reactive Mixture C) and an additional 5% PVP wasdissolved into Reactive Mixture C to form a Dye Containing ReactiveMixture.

3 mg of the Dye Containing Reactive Mixture was dosed into the center ofa Zeonor front curve lens mold. Next, 80 mg of Reactive Mixture C wasdosed on top of the Dye Containing Reactive Mixture. A polypropylenebase curve was then deposited and the molds were closed. The filledmolds were irradiated using Philips TL 20W/03T fluorescent bulbs aboveand below the lens molds and the following conditions: about 1 minute atabout 1 mW/sec² at ambient temperature, about 7 minutes at 2 mW/sec² and80° C. and about 4 minutes at 5.5. mW/sec² and 80° C. All curing wasdone in N₂. The molds were opened and lenses were extracted into a 70:30(wt) solution of IPA and DI H₂O at ambient temperature for at least 60minutes. The IPA:DI water solution was exchanged twice, and soaked inIPA:DI water at ambient temperature for at least about 30 minutes foreach additional exchange to remove residual diluent and monomers, placedinto deionized H₂O for about 30 minutes, then equilibrated in boratebuffered saline for at least about 24 hours and autoclaved at 122° C.for 30 minutes.

TABLE 3 Component Wt % SiGMA 28 PVP (K90) 7 DMA 24 mPDMS 31 HEMA 6Norbloc 2 CGI 1850 0.48 TEGDMA 1.5 Blue HEMA 0.02

Lenses of different powers were made. The lenses with relatively thincenter thicknesses (−1.00, 90 microns and −1.75, 120 microns) displayedsmooth radii, good optics and comfort. However, thicker lenses (>120microns, −6.00 power) displayed lenses having a flattened top, with pooroptics.

Examples 6-11

Photochromic Dye of Formula II

(6 wt % based upon the weight of the reaction components of reactivemixture) was dissolved into reactive mixtures shown in Table 4, to formdye containing reactive mixtures of Examples 6-11. D30 was added as adiluent in the amount listed in Table 4 (based upon the amount ofreaction components and diluent.

TABLE 4 Ex# 6 7 8 9 10 11 DMA 24 23.89 23.77 23.77 23.6 23.45 TEGDMA 1 11 1 1 1 HEMA 9.55 9.55 9.55 9.55 9.55 9.55 mPDMS 12.5 12.5 12/5 12.512.5 12.5 SiMMA 36 36 36 36 36 36 Norbloc 1.7 1.7 1.7 1.7 1.7 1.7Irgacure 0.25 0.36 0.48 0.48 0.65 0.8 819 PVP 15 15 15 15 15 15 %Diluent 29 29 29 35 35 35

3 mg of the dye containing reactive mixtures were dosed into the centerof Zeonor front curve lens molds. Next, 80 mg of Monomer mixture A wasdosed on top of the respective dye containing reactive mixture. Apolypropylene base curve was then deposited and the molds were closed.The filled molds were irradiated using Philips TL 20W/03T fluorescentbulbs (including UV filters within Zones 1 (A&B) and Zone 2A) above thelens molds at a constant 80° C. under the following conditions: about7.5 minutes at about 2.2 mW/sec² (Zones 1 (A&B) and 2A) and about 7.5minutes at 5.5 mW/sec² (Zones 2B and 3 (A&B)). All curing was done inN₂. The molds were opened and lenses were extracted into a 70:30 (wt)solution of IPA and DI H₂O at ambient temperature for at least 60minutes. The IPA:DI water solution was exchanged twice, and soaked inIPA:DI water at ambient temperature for at least about 30 minutes foreach additional exchange to remove residual diluent and monomers, placedinto deionized H₂O for about 30 minutes, then equilibrated in boratebuffered saline for at least about 24 hours and autoclaved at 122° C.for 30 minutes.

The sagittal depth at the center was measured for lenses made in eachexample and compared to a calculated ideal or design sagittal depthusing the following procedure.

A Nikon Scope SMZ1500 with component model numbers P-BERG (eye piece),P-IBSS (beam splitter camera port), DS-Fil (camera), P-FMD (mount), 1×WD 54 (lens), and base was used. An LED Backlight was arranged adjacentto a water bath with a 45° mirror placed under a Nikon Scope 1× lenssuch that the light emitted from the LED Backlight illuminates throughthe water bath and onto the 45° mirror which reflects up into the scope.See FIG. 9.

The scope and the NIS Elements D were set to 0.75×. The contact lens wasplaced into the water bath with the back curve side down. The contactlens and scope were adjusted so that contact lens is in focus on the PC.The lighting was adjusted such that back and front curve surfaces arevisible.

Utilizing the Radius tool in the NIS Elements D Software three pointsalong the back curve surface were selected on each side, such that acircumscribed circle was generated showing the “ideal” curvature of theback curve of the contact lens.

Utilizing the length tool the deviation of central photochromic regionwas determined by measuring the distance, at contact lens center,between the actual back curve surface of the contact lens and the“ideal” curvature. Where visibility of the base curve surface in thecentral photochromic region was limited, a point representing thelocation of the back curve surface was created. A point that representsthe back curve surface can be generated by measuring from the frontcurve surface through the contact lens for a distance equal to thecenter thickness of the contact lens. This set up was also used tophotograph the lenses shown in FIGS. 5-8.

The deviation from the ideal is listed in Table 5, below.

TABLE 5 Ex# [CGI 819] [diluent] Ave. dev. (mm) 6 0.25 29% −0.109 7 0.3629% −0.014 8 0.48 29% 0.057 9 0.48 36% −0.04 10 0.65 36% 0.0016 11 0.836% −0.0038

Example 12 and Comparative Examples 1 and 2

Lenses were made according to Example 6, using the dye monomer mixtureslisted in Table 6.

TABLE 6 Ex# 12 CE1 CE2 DMA 23.87 24 22.21 TEGDMA 1 1.25 1.5 HEMA 9.559.8 5.55 mPDMS 12.5 12 28 SiMMA 36 36 25.41 Norbloc 1.7 1.7 1.85Irgacure 0.36 0.23 0 819 Irgacure 0 0 0.48 1850 Blue 0.02 0.02 0 HEMAPVP 15 15 15 % Diluent 31 27 27

Lenses made in each of Examples 12 and Comparative Examples 1 and 2 werephotographed. The images are shown at FIGS. 5-7. As can be seen fromFIG. 5, the lens of Example 12 is well shaped and has a continuous curveacross the entire lens surface. The average percent deviation from thebase curve for five lenses is −4.5%.

The lenses of Comparative Examples 1 and 2 (FIGS. 6 and 7, respectively)show flattened tops, which deviate undesirably from the design sagittaldepth. In FIG. 6, the design curve has been drawn in with a light whiteline, and the design sagittal height at the lens center is designatedwith a small white box. Comparing FIGS. 6 and 7 with FIG. 5 (Example 6)shows the substantial improvement in hydrogel lens shape which can beachieved using the present invention. The average deviation measured forComparative Example 2 was −0.397 mm, which is more three times largerthan the deviation displayed by the lenses in Example 6 (−0.109 mm).

Example 13

Lenses were made according to Example 6, but using the photochromicmonomer mixture and clear monomer mixture listed in columns 2 and 3 ofTable 7 below. The photochromic monomer mixture contained 6 wt %photochromic compound of Formula II and 45 wt % decanoic acid as adiluents.

TABLE 7 Component PMM (wt %) CMM (wt %) Blue HEMA 0.02 0.02 DMA 18.918.9 Norbloc 2.2 2.2 OH-mPDMS 41.5 41.5 PVP K-90 12 12 TEGDMA 3 3 HEMA22.13 22.13 CGI 819 0.25 0.25 Decanoic acid (diluent) 45 60% t-amyl 45alcohol/40% decanoic acid

FIG. 8 shows a photograph of a lens made according to Example 13. Thelens is well shaped and the sagittal depth is within 100 microns of thedesign sagittal depth.

As stated prior, viscosity helps facilitate maintaining the photochromicwithin the central portion of a contact lens. However, in order toadjusts the viscosity of the inner (photochromic pupil) and outer(clear) monomers of a contact lens it is important to adjust the twomonomers in such a way that the hydrated swell of the final polymer(s)do not induce stress in the transitional region that occur between thephotochromic and non photochromic regions. The matching of the swell inthe transitional region can be made through adjusting the levels ortypes of monomer components such as hydrophilic monomers including2-hydroxyethyl methacrylate (HEMA), N,N-dimethyl acrylamide (DMA),N-vinyl pyrrolidone (NVP), N-methylacetamide, methacrylic acid,silicones, cross linker, polyvinyl pyrrolidone (PVP), polyacrylic acid(PAA), polymethylacetamide, polydimethyl acrylamide, PVA, and diluents.

The hydrogels of the present invention have water contents between about20 and about 75% water. In yet another embodiment the hydrogel contactlenses of the present invention have a water content of at least about25%. The lenses of the present invention may also have other desirableproperties, including a tensile modulus of less than about 200 psi, insome embodiments less than about 150 psi and in other embodiments lessthan about 100 psi. The lenses may further have oxygen permeabilities ofgreater than about 50 barrers, and in some embodiments greater thanabout 100 barrers. It should be understood that combinations of theforegoing properties are desirable, and the above referenced ranges maybe combined in any combination. In some embodiments it may be desirableto have the properties of the photochromic and non-photochromic polymerssubstantially matched (within about 10%).

A contact lens monomer generally includes a reactive mixture which maybe polymerized via exposure to actinic radiation. Monomer A maygenerally include a monomer with reaction components and diluent (D30)as listed in Table 1 which can be mixed together with stirring orrolling for at least about 3 hours at about 23° C., until all componentswere dissolved. The reactive components are reported as weight percentof all reactive components and the diluent is weight percent of finalreaction mixture. To form a lens, the reaction mixture may be placedinto thermoplastic contact lens molds, and irradiated with actinicradiation such as, for example, with fluorescent bulbs at 45° C. forabout 20 minutes in an N₂ atmosphere. The molds may be opened and lensesextracted into a 50:50 (wt) solution of IPA and H₂O, and soaked in IPAat ambient temperature for about 15 hours to remove residual diluent andmonomers, placed into deionized H₂O for about 30 minutes, thenequilibrated in borate buffered saline for at least about 24 hours andautoclaved at 122° C. for 30 minutes.

While the principles of the invention have been described herein, it isto be understood by those skilled in the art that this description ismade only by way of example and not as a limitation as to the scope ofthe invention. Other embodiments are contemplated within the scope ofthe present invention in addition to the exemplary embodiments shown anddescribed herein. Modifications and substitutions by one of ordinaryskill in the art are considered to be within the scope of the presentinvention, which is not to be limited except by the following claims.

What is claimed is:
 1. A hydrogel contact lens comprising: a pupillaryregion containing a pupil hydrogel composition containing a photochromicdye and an outer region formed from the reaction of a substantiallyclear monomer composition wherein said pupillary region is photochromicand concentric with said outer region; and said hydrogel contact lenscomprises a modulus of less than about 200 psi and a center sagittaldepth within 100 microns of design sagittal depth, wherein thephotochromic dye is formed from a compound selected from the groupconsisting of:


2. The contact lens of claim 1 wherein said pupillary region includes apupil hydrogel composition and the outer region is formed from thereaction of a substantially clear monomer composition wherein the pupilhydrogel composition contains a photochromic dye and is formed from areactive mixture having a higher viscosity which is at least about 1000cp higher than the clear monomer composition.
 3. The contact lens ofclaim 1 wherein said pupillary region is about 9 mm or less in diameter.4. The contact lens of claim 1 wherein said pupillary region has adiameter of between about 4 and about 7 mm.
 5. The contact lens of anyof claim 1 through 4 wherein said contact lens has a modulus of lessthan about 150 psi.
 6. The contact lens of claim 5 wherein said contactlens has a modulus of less than about 100 psi.
 7. The contact lens ofclaim 5 wherein said contact lens has an oxygen permeability of greaterthan about 50 barrers.
 8. The contact lens of claim 5 wherein saidcontact lens has an oxygen permeability of greater than about 100barrers.
 9. The contact lens of claim 5 wherein said contact lens has awater content between about 20 and about 75%.
 10. The contact lens ofclaim 5 wherein said pupillary region and said outer region, when cured,have water contents which are within 10% of each other.